# Referee Response: Balanced Panel Pre/Post-2000

Countries with patent data in BOTH pre-2000 AND post-2000: **42**

| Sample | N | Countries | R² | Z_1 coef | Z_1 SE | Z_1 p | Sig |
|---|---|---|---|---|---|---|---|
| Pre-2000 (balanced) | 279 | 42 | 0.2658 | -31.3546 | 7.4345 | 0.0000 | *** |
| Post-2000 (balanced) | 767 | 42 | 0.0378 | 5.4378 | 3.8604 | 0.1594 |  |
| Full pre-2000 | 286 | 44 | 0.2722 | -30.6473 | 7.3344 | 0.0000 | *** |
| Full post-2000 | 877 | 55 | 0.0341 | 6.9247 | 3.9962 | 0.0835 | * |

## Full Coefficients (Balanced Panel)

| Period | Variable | Coef | SE | p-value | Sig |
|---|---|---|---|---|---|
| Pre-2000 (balanced) | Z_1 | -31.3546 | 7.4345 | 0.0000 | *** |
| Pre-2000 (balanced) | Z_2 | 5.1157 | 1.2397 | 0.0000 | *** |
| Pre-2000 (balanced) | Z_3 | -0.2140 | 0.0546 | 0.0001 | *** |
| Pre-2000 (balanced) | rgdp_growth | 0.0016 | 0.0059 | 0.7897 |  |
| Pre-2000 (balanced) | kaopen | 0.1228 | 0.0597 | 0.0409 | ** |
| Post-2000 (balanced) | Z_1 | 5.4378 | 3.8604 | 0.1594 |  |
| Post-2000 (balanced) | Z_2 | -0.4623 | 0.5470 | 0.3983 |  |
| Post-2000 (balanced) | Z_3 | 0.0120 | 0.0216 | 0.5791 |  |
| Post-2000 (balanced) | rgdp_growth | 0.0051 | 0.0021 | 0.0141 | ** |
| Post-2000 (balanced) | kaopen | -0.0003 | 0.0319 | 0.9922 |  |

## Interpretation
Sign of Z_1 **flips** between pre- and post-2000 on the balanced panel, suggesting a genuine structural break rather than compositional artifact.
